Abstract:During the investigation and evaluation of Uranium deposits in Shiquantan area of Qaidam Basin,the formation pressure anomaly was encountered. The formation pressure coefficient of 0~600m is 1.25~1.4. The formation is easily soluble with a high salt content of up to 1.025%. Accidents such as stuck and collapse usually happened during the drlling process as drilling information about this area is less. In this paper, a set of anti-salt and anti-collapse flushing fluid system suitable for the strata in this area is proposed by analyzing the lithological characteristics of the strata in this area, and preferentially selecting the corresponding slurry-making clay and treatment agent for the flushing fluid. As a result, this systerm has good anti-salt and anti-collapse performance, mainly showing as follows: the apparent viscosity 38MPa·s, the dynamic shear force is 16.4Pa, the API filter vector is 4~5mL, the mud skin is thin and dense with the thickness of 0.3~0.4mm which has good wall protection effect. It effectively solved the problems such as shrinkage in salt-gypsum layers, hole collapse and destabilization of flushing fluid under abnormal conditions of high pressure in this area. As a result, the average monthly efficiency is increased from 729.76m to 1378.78m, the hole expansion rate is reduced from 130% to 19.4%, and the cost of mud material and water is reduced from 57.91RMB/m to 38.92RMB/m. Good economic benefits have been achieved in practical application in the field which make it has the value of popularization and application.